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Tracking The Latest At The Fukushima Nuclear Plant

March 18, 2011 2:01 PM ET

The situation at Japan's Fukushima Daiichi nuclear plant has been changing rapidly and growing increasingly complex since the earthquake and tsunami hit on Friday, March 11. Here, the latest updates on each of the reactors at the stricken power facility.

The situation at Japan's Fukushima Daiichi nuclear plant has been changing rapidly and growing increasingly complex since the earthquake and tsunami hit on March 11. Problems began that day, and each day has brought new, unsettling developments. With unique conditions at each reactor, slightly different responses are required. But the most common response at this point is water. Workers are pumping water into the cores of Units 1, 2 and 3 and adding water to the spent fuel pools at 3, 4, 5 and 6. Each reactor has a used fuel pool in the upper level of their buildings. Getting water to the spent fuel pools at Units 3 and 4 from the air and ground proved difficult for several days after radiation levels spiked. Safety officials say they continue to be most concerned about the pools at Unit 3 and 4. External power had reached most of the units by March 23. Below is a chart showing the status of each of the six reactors, with the most recent information as possible.

UPDATED: The information below reflects developments through 6:33 p.m. EDT March 29. It will continue to be updated as new information becomes available.

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Reactor No.1

A hydrogen explosion on March 12 severely damaged the outer reactor building. After using seawater to cool the overheating reactor core, fresh water is now being pumped through the nuclear reactor core. More than five feet of the fuel rods remain exposed inside the reactor.

Reactor No.2

A hydrogen explosion on March 15 damaged the reactor building and the pressure suppression chamber, causing the pressure inside the containment vessel to fluctuate. White smoke has been a regular occurrence from Reactor 2; seawater was initially pumped into the nuclear core but fresh water is now being used. Officials continue to pump seawater into the spent fuel pool.

Reactor No.3

A hydrogen explosion on March 14 was followed by smoke and the release of radiation on March 16. Helicopters and fire trucks have tried dousing the reactor building and spent fuel pools with water. About seven feet of the fuel rods are exposed inside the reactor core; after initially cooling the core with seawater, fresh water is now being injected.

Reactor No.4

Reactor 4 was undergoing routine maintenance at the time of the earthquake and tsunami, so there were no fuel rods in the reactor core. But the building was damaged by two fires on March 15 and 16, likely caused by a buildup of hydrogen from the rods in the spent fuel pool. Water has been regularly sprayed on the building and spent fuel pool using water cannons and concrete pumping trucks, and seawater has been added to the spent fuel pool.

Reactor No.5

Reactor 5 was shut down and undergoing routine maintenance at the time of the earthquake and tsunami. After running on emergency generators, electricity was restored to the unit on March 21, and cooling water systems have been repaired. Data from the reactor and spent fuel pool show normal temperatures and water levels.

Reactor No.6

Reactor 6 was shut down and undergoing routine maintenance at the time of the earthquake and tsunami. After running on emergency generators, electricity was restored to the unit on March 22, and cooling water systems have been repaired. Data from the reactor and spent fuel pool show normal temperatures and water levels.